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WASTE DISCHARGE REQUIREMENTS <br /> THE MARLEY COOLING TOWER COMPANY -2- <br /> STOCKTON, SAN JOAQUIN COUNTY <br /> b. Construction of covered storage facilities for treated wood to prevent <br /> contact with stormwater; and <br /> c. Discontinued use of arsenic compounds in wood treatment solutions . <br /> 8. Past use of copper, chromium, and arsenic wood treatment compounds has <br /> resulted in contamination of soils and ground water underlying the site. <br /> First ground water is approximately 40 feet below ground surface. The <br /> contamination sources are the Retort Pit and Stormwater Retention Pond (no <br /> longer in use) , identified in Attachment B. Soils have been contaminated <br /> With copper, chromium, and arsenic; ground water has been contaminated with <br /> chromium and copper only. A ground water contamination plume exceeding the <br /> Drinking Water Standard of 50 ug/l for chromium, extends off-site threatening <br /> local domestic supplies. <br /> 9. The Board, on 28 November 1984, ratified a Settlement Agreement between the <br /> Department of Health Services, the Discharger, and the Board, which requires <br /> the Discharger to define the extent of contamination, develop a mitigation <br /> plan , and implement all measures necessary to remediate existing site <br /> contamination. The Discharger is performing these tasks in accordance with <br /> the Agreement . <br /> 10. As part of the mitigation measures, the Discharger proposes to pump and <br /> discharge ground water from beneath the site to the on-site treatment plant <br /> before discharge. <br /> 11. The Report of Waste Discharge describes the combined stormwater and ground <br /> water characteristics prior to treatment as follows: <br /> Average Flow: 0.37 million gallons per day (mgd) <br /> Design Flow : 0.370 million gallons per day (mgd) <br /> Average Temperature: storm water - ambient <br /> ground water - 68°F <br /> Constituent Stormwater (m /1 ) Ground Water (mo/1 ) <br /> Total Chromium 5.0 20.0 <br /> Chromium VI 4.5 20.0 <br /> Copper 4.34 <0.05 <br /> Arsenic 0.04 <0.01 <br /> 12. Both stormwater and ground water will be treated at an on-site treatment <br /> plant constructed and operated by the Discharger. Treatment will consist of <br /> flow equalization, settling, filtration, pH adjustment, and ion exchange. <br />